Arm skin ulcers are generally considered due to contact dermatitis or eczema caused by, may also be due to trauma and other factors, daily should be reasonable diet, keep local clean. 1. Contact dermatitis: usually due to contact with allergens that stimulate the local skin, such as contact with animal hair or plants, and diet also has a certain relationship, usually leads to skin erythema, blisters, etc., such as usually do not pay attention to the care, may cause local infection, resulting in skin ulcers. 2. Eczema: eczema is a chronic inflammatory itchy skin disease, patients usually appear local pimples, erythema and accompanied by obvious itching symptoms, the patient is easy to cause skin ulcers after intense scratching. 3. Trauma: in some kind of outdoor sports, due to the lack of self-protection, knocked or stabbed, leaving wounds, without timely and appropriate care, may cause skin infections, which can lead to skin ulcers in severe cases. It is recommended that patients go to the dermatology department of regular hospitals to find out the cause of the problem and standardize the treatment under the guidance of doctors after a clear diagnosis.